Deceleration signaling apparatus having velocity and deceleration dependent signal

ABSTRACT

A deceleration signaling apparatus is provided for comparing actual vehicle deceleration with a reference deceleration and, when the actual vehicle deceleration exceeds the reference deceleration, integrates the net difference to generate a signal representing the difference between the actual vehicle velocity and a reference velocity determined by the reference deceleration. Means are provided for energizing signal lamps for providing deceleration warning while this velocity difference exceeds a predetermined constant. The comparator also functions to shift the magnitude of the reference deceleration from a first level to a second level less than the first level when the difference between the actual vehicle velocity and the reference velocity exceeds the predetermined constant so as to extend the duration of the deceleration warning.

Van Ostrom Feb. 26, 1974 DECELERATION SIGNALING APPARATUS HAVINGVELOCITY AND DECELERATION DEPENDENT SIGNAL [75] Inventor: David L. VanOstrom, Flint, Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Jan. 12 1973 [21] Appl. No.: 323,034

Primary Examiner-Alvin H. Waring Attorney, Agent, or Firm-Howard N.Conkey 5 7 ABSTRACT A deceleration signaling apparatus is. provided forcomparing actual vehicle deceleration with a reference deceleration and,when the actual vehicle deceleration exceeds the reference deceleration,integrates the net difference to generate a signal representing thedifference between the actual vehicle velocity and a reference velocitydetermined by the reference decel- 52 11.5. CI. 340/62, 340/262 eratien-Means are provided for energizing signal 51 Int. Cl B60q 1/44 lamps forProviding deceleration Warning While this 53 Fie|d f Search U 340 52 R,53 2 2 2; velocity difference exceeds a predetermined constant. 324/7 QThe comparator also functions to shift the magnitude of the referencedeceleration from a first level to a 56] f -Ci second level less thanthe first level when the differ- UNITED STATES PATENTS ence between theactual vehicle velocity and the reference velocity exceeds thepredetermined constant so 3 Sf Til i as to extend the duration of thedeceleration warning.

2 Claims, 2 Drawing Figures j A, 4! SC A N G R E S I 5 TO R V- \/E H l CLE SPEED DIFFERENTIATOR Z! S E in v 6' INTEGRATOR (10M PARATOR lREFERENCE SCALJNC; 5 VO L TAG E SUPPLY RESISTOR 1 a I! SIGNAL POWEROSCILLATOR LAMPS AMPLIFIER an indication of vehicle braking during andfor a predetermined time period after the braking operation and whichprovide a warning signal having a frequency and- /or duty cycle'that isa function of the magnitude of deceleration. As opposed to theaforementioned forms of deceleration warning devices, it is the generalobject of this invention to provide for a deceleration signalingapparatus in which the duration of the deceleration signal isa functionof both vehicle velocity and deceleration. I

It is another object of this invention to provide for a decelerationsignaling apparatus which provides an indication of the deceleration fora time period dependent upon the amount of braking both in the magnitudeof deceleration and vehicle velocity change.

It is another object of this invention to provide for a decelerationsignaling apparatus in which the duration of the deceleration signal iscontrolled by comprising actual vehicle deceleration with a referencedeceleration and determining the difference in the actual vehiclevelocity and a reference velocity determined by the referencedecleration and flashing signal lamps when the velocity differenceexceeds a predetermined value.

These and other objects of this invention are accomplished by monitoringthe vehicle speed which is differentiated to provide a signalrepresenting vehicle acceleration or deceleration. The vehicleacceleration or deceleration is summed with a reference deceleration andwhen vehicle deceleration exceeds the reference deceleration, the netdifference is integrated to provide a signal representing the differencebetween the actual vehicle velocity and a reference velocity. determinedby the reference deceleration. When this velocity difference exceeds apredetermined value, a comparator generates an outputsignal to energizean oscillator to effect the flashing of signal lamps, the duration ofthe flashing signal being dependent upon the velocity change and themagnitude of deceleration of the vehicle.

The invention may be best understood by reference to the followingdescription of a preferred embodiment and the drawings in which:

FIG. 1 is a block diagram of the deceleration signaling apparatus of thesubject invention; and

FIG. 2 is a graph of actual vehicle velocity and reference velocityversus time illustrating the dependency of the time duration of thedeceleration signal on the velocity change and magnitude of decelerationof the vehicle.

Referring to FIG. 1, there is shown the block diagram of an apparatuscarried by a vehicle to provide a deceleration warning signal rearwardthereof to following motorists. As shown therein, a vehicle speed sensor10 generates a DC voltage having a magnitude directly re,- lated tovehicle speed. The vehicle speed sensor 10 may take the form of any ofthe well known sensors for monitoring vehicle speed such as, forexample, a. wheel driven member having teeth which alter the reluctanceof a magnetic flux path to vary the flux threading a coil. The output ofthe coil of this form of sensor is then converted from a frequencyrepresenting wheel speed to a DC voltage representing wheel speed. ThisDC voltage is also representative of vehiclevelocity.

The output voltage of the vehicle speed sensor 10 is supplied to adifferentiator 12 which differentiates the output voltage and suppliescurrent to a summing junction 14 having a magnitude directly related toacceleration or deceleration of the vehicle. If the vehicle isaccelerating, current will flow from the differentiator 12 into thesumming junction 14 and if'the vehicle is decelerating, current willflow out of the summing junction 14 into the differentiator. Thedifferentiator 12 may take the form of a capacitor series coupledbetween the vehicle speed sensor 10 and the summing junction 14.

Vehicle acceleration and deceleration, as represented by the currentoutput of the differentiator 12, is summed at the summing junction 14with a first level of a reference deceleration as represented by aconstant current supplied to the summing junction 14 through a scalingresistor 16 by a reference voltage supply 18. The output of the summingjunction 14 is coupled to the negative input terminal of an integrator20 and is comprised of a current having a magnitude directlyproportional to the sum of the inputs thereto from the differentiator 12and the scaling resistor 16. As can be seen, this current will flow outof the summing junction 14 (a positive signal input to the negativeinput terminal'of the integrator 20) when the output of thedifferentiator 12 represents vehicle acceleration or represents vehicledeceleration with a magnitude less than the magnitude of the first levelof the reference deceleration and will flow into the summing junction 14(a negative signal input to the negative input terminal of theintegrator 20) when the output of the differentiator 16 representsvehicle deceleration with a magnitude greater than the first level ofthe reference deceleration.

The integrator 20 is of a conventional design which has both positiveand negative input terminals 'and functions to generate an outputvoltage representing the integral of the summation of the input currentsto those terminals. The integrator 20 can take the form of anoperational amplifier having capacitive feedback from its output to itsnegative input terminal. The integrator 20 also is of the known typehaving a lower output saturation level of zero volts. Consequently, whenthe integral of the summation of the inputs to the positive and negativeinput terminals is zero or negative, the output of the integrator 20 isat the lower saturation level of zero volts. Conversely, when theintegral of the summation of the inputs to the positive and negativeinput terminals is positive, the integrator 20 will generate a positivevoltage having a magnitude representing the integral.

The output of the integrator 20 is supplied to a comparator 22 having anoutput normally at zero volts. The

comparator 22 is responsive to a voltage input thereto above apredetermined threshold to shift its output to a positive voltage level.The output of the comparator 22 is coupled through a scaling resistor 24to the posi' tive input terminal of the integrator 20.

When the output of the comparator 22 is shifted to the aforementionedpositive voltage level, the current supplied to the positive input ofthe integrator through the scaling resistor 24 is effective fordecreasing the magnitude of the reference deceleration from the firstlevel to a second level as represented by the difference between thecurrent supplied to the summing junction 14 through the scaling resistor16 and the current supplied to the positive input of the integrator 20through the scaling resistor 24.

The output of the comparator 22 is also coupled to an oscillator 26which is energized when the output of the comparator 22 is at thepositive voltage level to supply pulsating power to a power amplifier 28which is periodically enabled thereby to flash a plurality of signallamps 30, the signal lamps 30 being flashed at the frequency of theoscillator 26 for the duration of the positive voltage output of thecomparator 22. The signal lamps 30 are positioned at the rear of thevehicle so as to provide deceleration warning to following motorists.

The operation of the system of FIG. 1 will now be described withreference to the plot of FIG. 2 in which velocity is plotted as afunction of time. As shown in FIG. 2, a dotted line 32 represents areference vehicle velocity and has a slope determined by the referencedeceleration and the solid lines 34, 36 and 38 represent three differentactual vehicle velocity profiles illustrating, in conjunction with thecurve 32, the subject invention.

Assuming the actual vehicle speed has been and is at a constant velocityV,, the output of the integrator 20 is at the lower saturation level ofzero volts. Consequently, the output of the comparator is at zero voltsand the oscillator 26, the power amplifier 28 and the signal lamps 30are deenergized. in addition, no current is supplied to the positiveinput terminal of the integrator 20 through the scaling resistor 24. Attime zero, the vehicle operator actuates the vehicle brakes and thevehicle begins to decelerate. At time T,, the vehicle decelerationexceeds the first level of the reference deceleration which results in anegative signal input to the negative input terminal of the integrator20, the signal having a magnitude representing the difference betweenactual vehicle deceleration and the first level of the referencedeceleration. Consequently, at time T,, the integrator 20 begins togenerate a voltage having a magnitude representing the integral of thedifference between the actual vehicle deceleration and the referencedeceleration. This integral is a direct measurement of the differencebetween the actual velocity of the vehicle and a reference velocityhaving the same magnitude as the actual vehicle velocity at time T anddecreasing therefrom at a rate equal to the first level of the referencedeceleration. This reference velocity is represented by the dotted linecurve 32 of FIG. 2 beginning at time T As long as the actual vehicledeceleration exceeds the first level of the reference deceleration, thedifference between the reference velocity and actual vehicle velocity,as represented by the output of the integrator 20, increases until attime T :1 predetermined velocity difference V is reached. As can beseen, this time is dependent upon the magnitude of the vehicledeceleration. The predetermined velocity difference V is represented byan input voltage to the comparator which equals the predeterminedthreshold. The comparator 22 then shifts its output from zero volts tothe positive voltage level. When the comparator 22 shifts its output tothe positive voltage level, the oscillator 26 is energized toperiodically pulse the power amplifier 28 which flashes the signal lamps30 to indicate to following motorists of the deceleration ex ceeding thereference deceleration. In addition, at time T when the output of thecomparator is shifted to the positive voltage level, the currentsupplied to the positive input of the integrator 20 through the scalingresistor 24 shifts the reference deceleration from the first level tothe second level as previously described. Consequently, at time T theslope of the reference velocity curve 32 changes to reflect the secondlevel of the reference deceleration, the second level being less thanthe first level.

Assuming the velocity profile represented by the solid line curve 34, inwhich curve the vehicle deceleration decreases to zero and the vehicleis then accelerated, when the vehicle deceleration decreases to a levelless than the second level of the reference deceleration, the magnitudeof the output voltage of the integrator 20 begins to decrease until attime T the difference between the reference velocity and the actualvehicle velocity decreases below the pre'detennined velocity differenceV At this time, the input to the comparator 22 decreases below thepredetermined threshold and the comparator 22 shifts its output from thepositive voltage level to zero volts to deenergize the oscillator toeffect termination of the deceleration signal.

Assuming the vehicle velocity profile illustrated by the solid linecurve 36, which curve represents a greater reduction of the velocity ofthe vehicle, it is not until time T that the output of the integratordecreases to a magnitude representing the predetermined velocitydifference V between the reference velocity and the actual vehiclevelocity to shift the output of the comparator 22 from the positivevoltage level to ground potential. As can be seen, the time durationthat the signal lamps 30 are flashed with the velocity profile 36 issubstantially greater than the time the signal lamps were flashed withthe velocity profile 34.

The velocity profile 38 assumes the vehicle is braked to a stop. As canbe seen, the signal lamps 30 are then flashed until time T at which timethe reference velocity decreases to the predetermined velocitydifference V at which time the comparator 22 shifts its output to groundpotential.

As can be seen from FIG. 2, the deceleration signal is a function of themagnitude of deceleration and also the velocity change during braking.In addition, it can be seen that if the vehicle is braked and thenaccelerated, the time duration that the signal lamps 30 are flahsed isreducedas compared to the'case where the vehicle is not accelerated.

The description of the preferred embodiment refers to two levels ofreference deceleration for illustration purposes only. It will beunderstood by one skilled in the art that the second level can beeliminated. Two levels of reference deceleration allows the use of thehigher level to prevent normal decelerations from implementing theflashing of the signal lamps 30 and the use of the lower level toprovide for an increased time duration of deceleration indication.

The detailed description of the preferred embodiment of the inventionfor the purpose of explaining the principles thereof is not to beconsidered as limiting or restricting the invention, since manymodifications may be made by the exercise of skill in the art withoutdeparting from the scope of the invention.

I claim:

l.'An apparatus for providing an indication of the deceleration of avehicle comprising: vehicle velocity sensing means for generating avelocity signal having a magnitude directly proportional to vehiclevelocity; differentiating means coupled to the vehicle velocity sensingmeans and responsive to the velocity signal for generating a rate signalrepresenting the rate of change of the vehicle velocity; means forgenerating a deceleration reference signal having a magnituderepresenting a predetermined deceleration warning level; means forsumming the rate signal and the deceleration reference signal andgenerating a resultant signal; integrating means coupled to the lastmentioned means and responsive to the resultant signal for generating avelocity difference signal having a magnitude representing the amountthat the time integral of the predetermined deceleration warning levelexceeds the vehicle velocity; comparator means coupled to theintegrating means and responsive to the velocity difference signal forgenerating a signal control voltage when the magnitude of the velocitydifference signal exceeds a predetermined threshold level; signal lamps;and means coupled to the comparator and responsive to the signal controlvoltage for energizing the signal lamps to provide an indication of thedeceleration of the vehicle, whereby said indication is dependent uponthe magnitude of deceleration and vehicle velocity change.

2. An apparatus for providing an indication of the deceleration of avehicle comprising: vehicle velocity sensing means for generating avoltage signal having a magnitude directly proportional to the vehiclevelocity; differentiating means coupled to the vehicle velocity sensingmeans and responsive to the velocity signal for generating a rate signalrepresenting the rate of change of vehicle velocity; means forgenerating a deceleration reference signal, said deceleration referencesignal being normally at a first level representing a firstpredetermined deceleration level and being shiftable to a second levelless than the first level, the second level representing a secondpredetermined deceleration level; means for summing the rate signal andthe deceleration reference signal and generating resultant signal;integrating means coupled to the last mentioned means and responsive tothe resultant signal for generating a velocity difference signal havinga magnitude representing the amount that the time integral-of thedeceleration reference signal exceeds the vehicle velocity; comparatormeans coupled to the integrating means and responsive to the velocitydifference signal for generating a control voltage when the magnitude ofthe velocity difference signal exceeds a predetermined threshold level;means coupled to the comparator means and responsive to the controlvoltage-for shifting I the reference deceleration signal from the firstlevel to the second level; signal lamps; and means coupled to thecomparator and responsive to the control voltage for fashing the signallamps to provide an indication of vehicle deceleration, whereby thedeceleration indication is a function of the magnitude of vehicledeceleration and the change in vehicle velocity.

1. An apparatus for providing an indication of the deceleration of avehicle comprising: vehicle velocity sensing means for generating avelocity signal having a magnitude directly proportional to vehiclevelocity; differentiating means coupled to the vehicle velocity sensingmeans and responsive to the velocity signal for generating a rate signalrepresenting the rate of change of the vehicle velocity; means forgenerating a deceleration reference signal having a magnituderepresenting a predetermined deceleration warning level; means forsumming the rate signal and the deceleration reference signal andgenerating a resultant signal; integrating means coupled to the lastmentioned means and responsive to the resultant signal for generating avelocity difference signal having a magnitude representing the amountthat the time integral of the predetermined deceleration warning levelexceeds the vehicle velocity; comparator means coupled to theintegrating means and responsive to the velocity difference signal forgenerating a signal control voltage when the magnitude of the velocitydifference signal exceeds a predetermined threshold level; signal lamps;and means coupled to the comparator and responsive to the signal controlvoltage for energizing the signal lamps to provide an indication of thedeceleration of the vehicle, whereby said indication is dependent uponthe magnitude of deceleration and vehicle velocity change.
 2. Anapparatus for providing an indication of the deceleration of a vehiclecomprising: vehicle velocity sensing means for generating a voltagesignal having a magnitude directly proportional to the vehicle velocity;differentiating means coupled to the vehicle velocity sensing means andresponsive to the velocity signal for generating a rate signalrepresenting the rate of change of vehicle velocity; means forgenerating a deceleration reference signal, said deceleration referencesignal being normally at a first level representing a firstpredetermined deceleration level and being shiftable to a second levelless than the first level, the second level representing a secondpredetermined deceleration level; means for summing the rate signal andthe deceleration reference signal and generating resultant signal;integrating means coupled to the last mentioned means and responsive tothe resultant signal for generating a velocity difference signal havinga magnitude representing the amount that the time integral of thedeceleration reference signal exceeds the vehicle velocity; comparatormeans coupled to the integrating means and responsive to the velocitydifference signal for generating a control voltage when the magnitude ofthe velocity difference signal exceeds a predetermined threshold level;means coupled to the comparator means and responsive to the controlvoltage for shifting the reference deceleration signal from the firstlevel to the second level; signal lamps; and means coupled to thecomparator and responsive to the control voltage for fashing the signallamps to provide an indication of vehicle deceleration, whereby thedeceleration indication is a function of the magnitude of vehicledeceleration and the change in vehicle velocity.